The proposed research will focus on the following areas of investigation I. Effect of Insulin treatment on "the terminal enzymes". 1. Relationship and role of glucose-6-P and -SH groups in glycogen synthetase D & I. 2. Conformational changes of glycogen synthetase by various ligands probed by fluorescent dyes. 3. Relationship between activation by citrate and dephosphorylation of acetyl CoA carboxylase. 4. Demonstration of the occurrence of phosphorylation and dephosphorylation of acetyl CoA carboxylase in vivo. 5. Studies on acetyl CoA carboxylase complex. lI. Effect of Insulin on Protein Phosphatase; this involved purification of various protein phosphatases involved in the activation and inactivation of "terminal enzymes" whose activities are modified by insulin action. III. Relationship between insulin action and Na-K ATPase. IV. Effect of nuclear glycogen accumulation on nuclear activity and the origin of nuclear glycogen observed with diabetes mellitus. All of these experiments are designed to elucidate the mechanism of insulin action.